Boots – shoes – and leggings
Patent
1993-02-25
1995-12-26
Swann, Tod R.
Boots, shoes, and leggings
395443, 39542109, 364DIG1, 235492, G06F 1202
Patent
active
054796377
DESCRIPTION:
BRIEF SUMMARY
CROSS-REFERENCE TO RELATED APPLICATION
This application claims a benefit of priority under 35 USC .sctn.119 based on French patent application 90 10858, filed Aug. 31, 1990.
BACKGROUND OF THE INVENTION
1. Field of Use
The invention relates to the use of memories and, more particularly, an object of the invention is a method and the corresponding device for the updating of information elements in a memory and the use of said method and device in memory cards.
In memory cards that enable the updating of information elements recorded therein, notably RAM or EEPROM type memories, as opposed to the EEPROM memories where the updatings by erasure and re-recording are not possible, a major problem relates to possible interruptions in supply during the updating. Indeed, if an interruption of the supply voltage takes place during the updating of an information element, it may be the case that the former value of the data element has been only partially erased or that the new one has been only partially written in the memory.
2. Description of Related Art
This problem exists notably for the updating of computer memories. Solutions exist in this field. They make use of supplies that are not subject to cuts, or of particular methods for the management of access to information, by software.
In the field of memory cards, such solutions are not applicable for it is impossible to maintain the supply without cuts and, since the resources are highly limited in terms of program size, the only solution that can be contemplated is that of an a posterior checking of erased or written data elements, during the final application, in order to detect and then correct the errors if any.
SUMMARY OF THE INVENTION
An object of the invention is a method, and the corresponding device, for the updating of information elements in a memory that makes it possible, with a minimum use of resources, to ensure that the information that has to be updated is in a known state before the updating or after the updating, but never in an indeterminate state, and consequently makes it possible to carry out a transaction without ambiguity irrespectively of the instant of interruption, in the event of a problem.
According to the invention, the method for the updating of information elements in a memory is characterized in that, for the updating of a data element (D), an initial or preceding value (D0) of which has been written in the memory at a first memory location (E0), the method comprises the following steps: another memory location (E1), and is associated with a logic indicator that is initially in a first logic state, kept in this state during an updating; value being guaranteed in the event of coincidence with the value whose writing has been activated, and an error code being emitted in the event of non-coincidence; second logic state of the logic indicator, the updated value being then accessible in reading mode.
An object of the invention is also the device designed for the implementing of this method.
It is also an object of the invention to use a method such as this and a device such as this in memory cards.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be understood more clearly, and other features will be revealed by means of the following description, made with reference to the appended figures.
FIGS. 1 and 2 respectively illustrate the steps of the updating method and the device designed for its implementation according to a first alternative embodiment.
FIGS. 3 and 4 respectively illustrate the steps of the updating method, and the device designed for its implementation according a second alternative embodiment.
DESCRIPTION OF PREFERRED EMBODIMENTS
In a re-recordable memory of the EEPROM or RAM type, the safeguarding of an operation for the writing of a data element is most usually done only after a prior operation for resetting the corresponding memory location at zero. Furthermore, the writing operation can generally be done only once. The writting of a data element is done by bits, bytes or words. Consequently, as i
REFERENCES:
patent: 4339804 (1982-07-01), Davison et al.
patent: 4442345 (1984-04-01), Mollier et al.
patent: 4493083 (1985-01-01), Kinoshita
patent: 4827115 (1989-05-01), Uchida et al.
Lisimaque Gilles
Paradinas Pierre
Gemplus Card International
Nguyen Hiep T.
Swann Tod R.
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